Catalysis 2025 Issue

Aspect ILs tend to have high viscosities at ambient tempera- tures, which can limit mass transfer rates, although the high removal efficiencies result from a large mass transfer driving force. The adsorption of organics from spent caustic solutions on bleaching earth, alumina, and petroleum coke has been reported under alkaline conditions.3 Optimal mesoporous  NaY  Cost Medium Low Low Very low Bleaching earth could reduce COD values by 60%, prob- ably by ion exchange and/or intercalation of the organic ani- ons between layered structures. However, alumina-based adsorbent reacted chemically with alkali, resulting in adsor- bent bed collapse in the column. SiO₂/AI₂O₃ ratio Mesoporosity High High for the doubled middle distillate yield compared to the other mesoporous sample, as well as the surprisingly increased activity compared to the conventional USY zeolite. Multiplication of the relative strong acidity with the mes - opore volume yields a much-improved relationship with the middle distillate yield (see Figure 5, left ). Similarly, the activity number relates better to the activity of the cata - lysts (see Figure 5, right ). These descriptors highlight the need to prioritise both mesopore quantity and quality in the synthesis of superior high-quality USY zeolites for hydrocracking. Integrated dealumination and mesoporisation Having a high-quality USY zeolite does not necessarily imply commercial relevance (Figure 3). For example, even if a high-quality mesoporous zeolite can be achieved without the need for costly organics, the dependency on a costly high-silica-alumina-ratio (SAR) starting USY complicates the business case. The phase separation needs to be improved by a solvent extraction step, using an organic solvent that can dissolve the separated phenolic oil. However, neutralisation by CO 2 is restricted to free alkali and alkali salts of phenols. Thiophenols and all naphthenic acid(s) remain in the solu- tion because of their stronger acidic nature. Zeopore researchers have dedicated significant effort to stepping away from the state-of-the-art linear mesop - orisation path (see Table 1 ), exploring the various routes present in the faujasite landscape to arrive at a mesoporous high-SAR USY. In doing so, the classical dealumination fol - lowed by the mesoporisation route is abandoned, opening up a wide variety of synthetic options within the two- dimensional faujasite landscape. In this landscape, the researchers have managed to avoid the many pitfalls, overcome stubborn challenges, and exploit unexpected synergies. They have established a route that not only attains the required high-quality USY zeolite but does so using exclusively scalable and low-cost ingredients, including the parent zeolite. The treatment of highly alkaline waste streams using CO 2 provides a sustainable solution. The phenolic compounds are removed by bringing the pH of the solution below pKas of phenol(s) and efficiently separating the oil phase. (In molecular form, phenol and cresylic acids have poor solu- bility in water). The limitation of slower solubilisation of CO 2 due to its poor solubility in water can be overcome using a suitable unit to increase mass transfer area between gas and liq- uid phases, allowing maximum CO₂ use in the process. It is also possible to use gaseous effluent from thermal energy plants or refineries, having CO₂, nitrogen (N₂), nitrogen oxide (NOx) and sulphur dioxide (SOx), depending on fuel type. However, if SOx and NOx are present, they will react faster than CO₂ and further reduce the pH. The risk of H2S evolution remains in such a case if pH drops to an acidic Table 1 With petroleum coke, there was no removal of COD com- ponents from the spent caustic. Instead, the spent caustic desorbed other organic compounds, increasing the COD values. It is not surprising due to the ionic nature of organic compounds under strongly alkaline conditions. The result- ing contribution to the COD does not allow their adsorption on coke. When pH is reduced and phenolic compounds are converted into a molecular form in the present studies, their adsorption on activated carbon improves significantly. Conclusion

Conventional USY In refineries, the spent caustic stream is mixed with other aqueous solutions, diluting the spent caustic effluent. If the spent caustic from the kerosene treatment unit, with its remarkably high load of phenolics, is treated directly with CO 2 , the process may provide an economic incentive to recover phenols as a valuable product.  State-of-the-art mesoporous Medium Very high High Low High High Outlook By understanding the complex material properties and exploiting synthetic potential, unique mesoporous USY zeolites and related means of manufacture have been cre - ated. This advancement creates a valuable position to bring the promising catalytic benefits of accessible USY zeolites to the refiner. References 1 D. Verboekend et al ., Synthesis, characterisation, and catalytic evalua - tion of hierarchical faujasite zeolites: milestones, challenges, and future directions, Chemical Society Reviews, 2016, 45, 3,331-3,352. 2 K. Du Mong, D. Verboekend, Low-cost mesoporous zeolites deliver catalytic benefits, PTQ Catalysis , 2022, 45-49. 3 S. Torrisi, J. Den Breejen, Boosting hydrocracker heavy feed conver - sion, PTQ Catalysis , 2020, 1-7. 4 D. Verboekend, Enhancing C8+ aromatics conversion, Hydrocarbon Engineering , November 2024. 5 K. De Jong et al., Zeolite Y crystals with trimodal porosity as ideal hydro - cracking catalysts, Angewandte Chemie , 2010, 49, 10,074-10,078. 6 L. Vaugon et al. , Impact of pore architecture on the hydroconversion of long chain alkanes over micro and mesoporous catalysts, Petroleum Chemistry , 2020, 60, 479-489. 7 T. C. Keller et. al., Design of hierarchical zeolite catalysts for the manufacture of polyurethane intermediates, ACS Catalysis , 2015, 5, 734-743. 7 Sabri, M.A., Ibrahim, T.H., Khamis, M.I., Nancarrow, P., Hassan, M.F., (2018) Spent caustic treatment using hydrophobic room temperatures ionic liquids, J. Ind. Eng. Chem ., 65, 325–333, https://doi.org/10.1016/j. jiec.2018.05.002. 8 V. Rac et al. , Hierarchical ZSM-5, Beta and USY zeolites: Acidity assessment by gas and aqueous phase calorimetry and catalytic activ - ity in fructose dehydration reaction, Microporous and Mesoporous Materials, 2014, 194, 126-134. Danny Verboekend is a founder and CSO of Zeopore Technologies. He is engaged in the strategic development of novel materials using strictly low-cost and scalable manufacturing routes, for established and novel (circular) catalytic applications. Vaibhav B Kamble is a post-graduate student in the Department of Chemical Engineering at the Institute of Chemical Technology, Matunga, Mumbai-400019, India. level, demanding a secondary treatment unit for the cap- ture of H 2S. We believe that using a CO 2 waste stream to treat another waste solution is a sustainable solution. Such positive solu - tions can have a positive and profitable effect across the entire spectrum of the oil industry. References 1 Pino-Cortés, E., Montalvo, S., Huiliñir, C., Cubillos, F., Gacitúa, J., (2020) Characteristics and Treatment of Wastewater from the Mercaptan Oxidation Process: A Comprehensive Review, Processes , 8, 425; doi:10.3390/pr8040425. 2 Rita, A.I., Rodrigues, C.S.D. Santos, M. Sanches, S. Madeira, L.M., (2020) Comparison of different strategies to treat challenging refin - ery spent caustic effluents, Sepn. Purifn. Technol., 253, 117482-97, https://doi.org/10.1016/j.seppur.2020.117482. 3 Czimer, B., Kovács, A., Petró, J., (2015) Treatment of Spent Merox Caustic Waste in Industrial Ecology Frames, Period. Polytech. Chem. Eng. , 59(3), 215-220, DOI: 10.3311/PPch.7601). 4 Roudsari, M. H., Soltani, M., Seyedin, S. H., Chen, P., (2017) Investigation on New Method of Spent Caustic Treatment, J. Multidisc. Eng. Sci. Technol. , 4(6), 7459-7464. 5 Kumfer, B.J., Felch, C.L., Brandenburg, B., Ishmann, R.R., (2014), US patent, 8,734,648 B2, Siemens Energy, Inc., Orlando, FL (US). 6 Doble, M., Kruthiventi, A. K., Gaikar, V.G., (2004) Biotransformation’s and bioprocesses, Marcel Dekker, New York. Dr Vilas G Gaikar is Bharat Petroleum Chair Professor. Email: vg.gaikar@ictmumbai.edu.in K V Seshadri is Adjunct Professor in the Department of Chemical Engineering at the Institute of Chemical Technology, Matunga, Mumbai-400019, India.

Distinct routes for preparing mesoporous USY zeolites for hydrocracking

SCAN HERE FOR A FREE SUBSCRIPTION

Catalysis 2025 PTQ Q1 2025